Juvenile myelomonocytic leukemia (JMML) is a rare, fatal childhood disease that affects infants and young children less than 4 years of age. JMML is characterized by aberrant myeloid cell overproduction and hypersensitivity to GM-CSF. The only curative therapy is allogeneic hematopoietic stem cell transplantation; however, approximately half of children relapse after this aggressive therapy. Thus, while great advances have been made in understanding the molecular basis for JMML (caused by mutations inducing gain-of- function of the RAS-ERK signaling pathway), unfortunately, improved therapies for this disease remain to be defined and are urgently needed. Over several years, an international community of families, scientists, and clinicians have merged their efforts to advance the research and improved treatment for JMML. A key unifying aspect of this collaborative effort has been the bi-annual International JMML Symposia alternating with bi-annual JMML Working Groups which precede the annual American Society of Hematology (ASH) meetings. These pre-ASH meetings (supported by the NCI via this R13 conference grant since 2007) provide the perfect locale for gathering of JMML clinicians and scientists from Europe, Japan, and the United States, and afford an efficient means of stimulating open communication and collaboration between the various groups. An international approach to this disease is particularly imperative since JMML is a rare disease. The annual symposium organized and sponsored by the JMML Foundation has four major goals: 1. to share the latest developments in JMML scientific and clinical research by fostering high level presentations from leading national and international leaders in the field; 2. to provide a venue for planning and implementing innovative clinical trials for patients with this disease; 3. to facilitate communication between JMML investigators and patient advocates; and 4. to provide a forum in which junior investigators in JMML can present their work and interact with each other and with senior investigators in the field. We seek support for the 2015 JMML International Symposium, which will be held in conjunction with the American Society of Hematology annual meeting in Orlando, FL. The PI for this meeting, Rebecca J. Chan, M.D., Ph.D., is a member of the JMML Foundation Board of Directors and researcher in the field. Additionally, Mignon L. Loh, M.D., a JMML researcher and clinician, Mr. Fred Dini, President of the JMML Foundation, and Dr. Sandra Thomas, will also be part of the conference planning team.